arXiv Machine Learning

Multitask Regression with Pairwise Fusion

The paper investigates multitask regression where different predictors may have varying degrees of coefficient sharing across tasks. It introduces a framework that quantifies sharing by the number of active predictors and the total number of task-specific coefficient deviations, and proposes a pairwise penalty estimator that achieves matching upper and lower bounds in terms of these quantities. The method also handles scenarios where a large subset of tasks shares an identical coefficient vector, with explicit sample‑size conditions ensuring exact pooling of those tasks while allowing others to differ.

arXiv Machine Learning
Sep 10

Multi-Task Learning with Covariate-Overlap Regularization

The paper introduces COVER, a multi‑task learning framework that regularizes covariate overlap to mitigate the negative effects of sharing information across tasks with differing covariate distributions and response relationships. COVER blends a common component function, a shared neural representation, and low‑dimensional task‑specific coefficients, using taskwise second‑moment matrices to guide coefficient integration. The authors provide theoretical bias‑variance analysis, oracle inequalities, and neural‑network convergence rates, and demonstrate that COVER outperforms existing deep‑learning and statistical integration methods in simulations and a GTEx central‑nervous‑system study.

By Yang Sui, Qi Xu, Yang Bai, Annie Qu
arXiv Machine Learning
1d ago

Model Merging via Data-Free Covariance Estimation

The paper introduces a data‑free method for model merging that estimates per‑layer covariance matrices directly from difference matrices, eliminating the need for auxiliary data. This approach reduces computational costs while maintaining a principled interference‑minimization framework. Experiments on vision and language benchmarks with models from 86 M to 7 B parameters show that the method outperforms existing data‑free merging techniques.

By Marawan Gamal Abdel Hameed, Derek Tam, Pascal Jr Tikeng Notsawo, Colin Raffel, Guillaume Rabusseau
arXiv Machine Learning
Sep 22

Not All Ranks Are Equal: Budget-Aware LoRA Merging Across Tasks

The paper introduces Net Utility, a data‑free metric for selecting which singular directions of low‑rank adapters (LoRAs) to keep when merging across tasks. By scoring each direction for task utility and interference, and then globally selecting the highest‑scoring directions under a total budget constraint, the method avoids the uniform‑budget assumption that hampers existing merging techniques. Experiments on vision and language tasks show that Net Utility‑based rank allocation yields about a 2% performance gain over other merging methods.

By Avinash Amballa, Yashas Malur Saidutta, Wenbo Li, Lazar Valkov, Srinivas Chappidi
arXiv Machine Learning
Aug 27

Escaping Low-Dimensional Overlap: Multi-Task Model Merging via High-Dimensional Sparse Disentanglement

The paper introduces a new multi‑task model‑merging framework that tackles task interference by projecting task vectors into a high‑dimensional sparse feature space using Sparse Autoencoders, enabling feature‑level disentanglement before fusion. It also proposes a lightweight Group‑Ranked Zeroth‑Order Optimizer to identify task‑critical layers for selective merging, reducing computational overhead. Experiments on Qwen2.5‑1.5B and Qwen2.5‑7B show consistent performance gains over several baselines across reasoning, code generation, instruction following, and general knowledge tasks, with a 2.78% improvement in a highly conflicting four‑task setting.

By Yihang Zhang, Shengke Sun, Junjie Wen, Feng Zeng